1. Field of the Invention
The present invention relates generally to an apparatus and method for reducing the risk of environmental contamination by toxic chemicals, and, in particular, to an apparatus and method for reducing the risk of environmental contamination by mercury and mercury salts used during the removal of gold ballbonds from the pads of a semiconductor device.
2. Description of Related Art
In the course of the failure analysis of semiconductor devices, one of the first steps involves the removal of the gold ball bonds that are used to connect the pads of the semiconductor device to the module leads. It is well known that gold will dissolve in liquid mercury and the technique is used to remove the gold ball bonds from semiconductor pads. For example, in U.S. Pat. No. 5,424,254, a semiconductor chip is laid down to float in an agitated mercury bath to remove gold ball bond connections. Generally, the technique involves black waxing the semiconductor device to a glass slide which is then dipped into a beaker of mercury, then into a beaker of nitric acid, then in a beaker of water, and then rinsed under a spigot in a sink. This process can be carried out manually, or more commonly by an automated carrier transfer system. In U.S Pat. No. 5,429,642, a method and apparatus is disclosed for transferring wafers from one processing station to another in a clean room or on a clean bench, to be dipped into a chemical liquid at each station.
During the gold ball bond removal process, when the dipped slide is removed from the mercury bath, particles of mercury remain attached to the slide and semiconductor device and are carried over into the nitric acid bath. These residual particles are dissolved in the nitric acid bath. The nitric acid is then removed from the slide and device by the water rinse. During the water rinse, it is possible for dissolved mercury to precipitate out as liquid mercury. It is also possible, that during movement of the slide from bath to bath, mercury particles, acid containing mercury salts, or water containing mercury salts, will spill or drip from the slide and down onto the work space or area. For health and environmental reasons, liquid mercury and liquids containing mercury salts cannot be allowed to remain on equipment or be flushed down industrial drains. While the automated transfer system reduces the risk of direct human contact with mercury or other toxic liquids, the containment of contaminants and spillage during the gold ball bond connection removal process and preventing contaminants from being introduced into an industrial waste line remains a problem.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide an apparatus and method which will reduce mercury contamination of the environment during the gold ball bond removal process.
Another object of the invention is to provide a method and apparatus to contain mercury spillage during carry over between processing tanks during the gold ball bond removal process.
Yet another object of the invention is to provide a method and apparatus to reduce the risk of environmental contamination and the discharge of mercury and mercury salts into industrial waste lines during the gold ball bond removal process.
Still another purpose of the invention is to provide an apparatus for gold ball bond connection removal which is self-contained, compact in size, efficient and yet environmentally safe.
Yet another purpose of the invention is to provide a self-contained, compact, environmentally safe system for use with toxic chemicals and liquids.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.